Automatic measurement apparatus

ABSTRACT

An automatic measurement apparatus is provided which employs a device for scanning work to be measured by the relative movement of a sensor and the work whereby the sensor senses one or more surfaces of the work. Means are provided for generating code signals indicative of the relative movement and further means are provided for visually presenting information as a readout which indicates the locations of one or more surfaces with respect to a base or bench mark location. In a particular form of the invention, the distance between two surfaces may be automatically indicated on said readout device.

Umted States Patent 1151 3,636,635 Lemelson 51 Jan. 25, 1972 [54] AUTOMATIC MEASUREMENT 3,164,909 1/1965 Rosenberg ..33/174. APPARATUS 3,250,012 5/1966 Hilton et al ....33/l74 L 3,410,956 1 H1968 Grossimon et al ..33/l M [72] Inventor: Jerome H. Lemelson, 85 Rector St,,

Metu hen, NJ, 08840 FOREIGN PATENTS OR APPLICATIONS [22] Filed: Oct. 7, 1969 892,873 1/1944 France ..33/l72 E [21] Appl. No.: 864,510 OTHER PUBLICATIONS Related US. Application Data Pub. Measure Position Digitally, Control Engineering, Nov. 1956 by W. H. Klievcr [63] Continuation-in-part of Ser. No. 518,616, Jan. 3,

1966, Pat. No. 3,476,481. Primary Examiner--Harry N. Haro'ian [52] US. CL. ..33/174 L 57 ABSTRACT [51] Int. Cl ..Glb /00,G0lb 11/00 58 Field of Search ..33/174, 18, 125, 23 c, 1 M; An automatic measurement apparatus 18 Provided whlch 3 05 ploys a device for scanning work to be measured by the relative movement of a sensor and the work whereby the sensor [56] Refer Ci d senses one or more surfaces of the work. Means are provided for generating code signals indicative of the relative move- UNITED STATES PATENTS ment and further means are provided for visually presenting information as a readout which indicates the locations of one g or more surfaces with respect to a base or bench mark loca- 2'628539 2/1953 Nmann C tion. in a particular form of the invention, the distance 2'77O798 1 1956 h eergaar "33/125 C between two surfaces may be automatically indicated on said 0! readout device. 2,775,755 12/1956 Smk ..33/125 C 3,076,374 2/1963 Ncergaard ..33/l25 C 12 Chims 15 Drawing Figures M My WK 83 1 81 IS 84 I DIGITAL MAX Ax' 8") 8| coururen c a9 2 0 1 coum'zn 8 nuoour 9| CA1 97 O0 Pmemiumzsmz 3,636,635

SHEET 2 UF 6 REVERSIBLE 55 54' 54 52 52' A I if Q 54 O I l 52 FIGS INVENTOR. JEROME H. LEMELSON FIG.6 J2 J3 MI PATENTED JAN25I972 3, 3 ,635

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INVENTOR. Jerome H.Lemelson PATENTED JAN251972 3.636.635

sum 5 OF 6 In ||4\ ma F SENSOR S PROBE PROBE MANIPULATOR MOTOR A R'M R J "2 H? MASTER J CONTROLLE |2O PULSE RANSFORM INVENTOR. Jerome H.Lernelson AUTOMATIC MEASUREMENT APPARATUS RELATED APPLICATIONS This is a continuation-in-part of application Ser. No. 518,616 filed Jan. 3, 1966, for Automatic Measurement System now U.S. Pat. 3,476,481, which was a continuation-inpart of Ser. No. 250,942 filed Jan. I l, 1963, now US. Pat. No. 3,226,833 having as a parent application Ser. No. 477,467 filed Dec. 24, 1954 now abandoned.

SUMMARY OF THE INVENTION This invention relates to an automatic inspection apparatus which employs, in one form, an inspection probe which is power operated and automatically controlled in movement to sense one or more surfaces of a work piece. Automatic measurement of the location of said workpiece surfaces and/or dimensions between surfaces is effected by generating signals indicative of the degree of movement of the probe from a starting location or from one surface to a surface being measured. In another form, the invention employs a photoelectric scanning device including a light source and a photoelectric cell which are utilized to detennine the locations of surfaces or dimensions between surfaces by variations in light received by the photoelectric cell resulting from light from the light source being intercepted by portions of the work.

Before the making of the instant invention, it was known in the art to provide measurement apparatus which would record markings on a chart or drum which were indicative of a graph or profile of the surface being measured. US. Pat. No. 2,697,879 discloses such an apparatus but, in order to obtain an indication of the dimensions being measured, which indication could be utilized either by a machine operator adjusting a machine tool or by a computer, it is necessary to scale and measure dimensions on the graphic recordings. Such an operation is not only tedious and time consuming but frequently results in errors introduced during the manual measuring operation and, quite often, the procedure is not sufficiently precise to permit the application of such apparatus for various production and quality control operations.

Accordingly, it is a primary object of this invention to provide a new and improved automatic inspection apparatus and method for deriving information representative of dimensions, surface locations and variations from tolerance in an automatic manner and presenting such information in visually readable digital or character form.

Another object is to provide an automatic inspection apparatus which is versatile and may easily be applied to the measurement of dimensions of a variety of difierent sizes and shapes of work and may be utilized by operators having various degrees of skill.

Another object is to provide an automatic inspection apparatus which presents information to an operator in a form which is readily utilizable by said operator for correcting or adjusting a machine or tool.

Another object is to provide an automatic inspection apparatus which may easily be adapted to provide information for computerized quality control and machine automatic control.

Another object is to provide an automatic inspection apparatus employing a precision optically readable coded scale and a photo-optical reading means for determining the movement of an inspection probe and/or movement or a workpiece in a precise manner and in a form which may be readily utilized by a computer.

With the above and such other objects in view as may hereafter more fully appear, the invention consists of the novel constructions, combinations and arrangements of parts as will be more fully described and illustrated in the accompany drawings, but it is to be understood that changes, variations and modifications may be resorted to which fall within the scope of the invention as claimed.

In the drawings:

FIG. 1 is an end elevational view of an automatic dimensional-measuring apparatus having movable jaws for engaging adjacent or opposite surfaces of a workpiece;

FIG. 2 is an end elevation showing an automatic measuring apparatus having a plurality of movable and programmably adjustable surface sensing probes;

FIG. 3 is a side view, with parts broken away for clarity, of work-measuring jaws applicable to the apparatus of FIG. 1;

FIG. 4 is a side view, with parts broken away for clarity, of surface-sensing jaw elements having grounding or noncontacting surface-sensing means;

FIG. 5 is an end view of the apparatus of FIG. 4 with parts broken away for clarity;

FIG. 6 is a side view showing an arrangement of manipulator elements including surface-sensing probes applicable to the apparatus of FIG. 2;

FIG. 7 is a schematic diagram showing means for controlling the apparatus illustrated in FIGS. 1 and 3 and applicable also to the other automatic measuring apparatus of this invention;

FIG. 8 is a partial view, with parts broken away for clarity, of a portion of the apparatus of FIGS. 3 and 7;

FIG. 9 is a schematic diagram showing control elements operative for efiecting the automatic measurement of dimensions by optical scanning and also applicable to the apparatus of the other FIGS.;

FIG. 9' and 9a show other forms of the invention;

FIG. 10 is an end view of a photoelectric housing applicable to the apparatus of FIG. 9;

FIG. 11 is a cross-sectional side view of the housing of FIG. 10;

FIG. 12 is an end view of a modified view of the housing illustrated in FIG. 11; and I FIG. 13 shows an automatic scanning system applicable to indicate probe or work movement in an apparatus of the types provided in the other drawings.

In FIG. 1 an automatic measuring apparatus 10 is movable along an overhead track 11 and/or a floor mounted track 21 for prepositioning its measuring head assembly 31 relative to work-in-process generally designated W. The work W may be prepositioned on a base 9 which may comprise a worktable or a conveyor adapted also to bring the work into alignment with the measuring apparatus 10.

The measuring apparatus 10 is shown having a programming control CO mounted in a housing secured to the apparatus which preferably includes easily presettable or programmable control elements operatively connected for controlling the various servomotors associated with the measuring apparatus to preposition the measuring head, for example,

' directly over the portion of the workpiece or assembly W to measure a dimension such as D. The programming controller CO may consist of a plurality of manually presettable dials for presetting precision resistors, counters or switching circuits for controlling the movement of the components to be described whereby the measuring head 31 is moved through a predetermined path relative to the workpiece. In addition to prepositioning the measuring head 31, the controller CO preferably further eflects movement of one or more contact or proximity probes associated with 31 which are automatically stopped and retracted upon sensing a surface comprising one of the plurality of surfaces across which measurement is desired. Initiation of the operation of controller CO may be manually effected once the assembly 10 is in a predetermined position relative to the workpiece W or by automatic meansas will be hereinafter described.

The automatic measuring apparatus comprises in FIG AN OVERHEAD CARRIAGE -0 SUPPORTING A VERTICAL COLUMN -0 WHICH IS SHOWN ROTATIONALLY MOUNTED AND DEPENDING DOWNWARD FROM -0. A first motor Mx is secured to the carriage l2 and is preferably a gear motor having a drive wheel 16 having peripheral teeth and secured to the shaft of Mr and urged thereby to engage a shaped portion of the overhead track for longitudinally driving assembly therealong. In a similar manner, a drive motor such as Mx may be secured to the carriage or retainer 20 at the lower end of 13 for urging said assembly along the floor mounted track 21.

A fixture 24 which includes the measuring head assembly 31 depends outward from a base or carriage 25 adapted for moving vertically along the column 13 to position the measuring head assembly in the vertical direction. A large spur gear 15 is shown secured to the upper end of 13 which is engaged by a smaller spur gear 14 secured to the shaft of a motor MR which is secured to the upper carriage l2 and is controlled in its operation by signals from programming controller CO to rotate column 13 for prepositioning measuring head 31 in a plurality of cylindrical paths. Wheels 17 rotationally supported on the carriage 12 engage the lower portion or flange of the overhead track and further wheels supported by the lower carriage 20 also engage the lower track 21 for movement of the assembly longitudinally along the two tracks.

Projecting outward from 25 is an assembly including a first cylindrical arm member 26 mounting a first gear motor MR2 the shaft of which mounts a gear 27 which engages a larger gear 28 secured to a second arm 26' which is thereby rotatably relative to 26 by means of said motor. The other end of arm 26' contains a rotational joint 29 which pivotally supports a third arm Ax which internally mounts a third gear motor MAl not shown for pivoting Ax relative to 26'. The other end of Ax contains a pivoting joint 30 and a fourth gear motor MA2 which is operative to rotate a portion of the joint 30 including the measuring head assembly 31 relative to Ax. As stated, all of the hereinabove-described drive motors contain respective start, stop, reverse and speed controls which are operatively coupled to and controllable by the controlling programmer CO by means illustrated in my said copending application. The measurement head 31 is thus prepositioned relative to the workpiece W by the automatic and predetermined control of said servomotors and is preferably operative thereafter to engage one or more surfaces of said workpiece aligned with the assembly 10 and to effect automatic measurement across predetermined portions of the workpiece.

Notations SW] and SW2 define indicating or sensing means positioned on or within movable portions 32 and 33 of the measuring head 31 for sensing surfaces of work W and indicating by generating electrical signals when a particular surface is in contact with or immediately adjacent said sensing means. The sensors SW may comprise electromechanical limit switches adapted with actuator means operative upon engagement of a workpiece surface, surface proximity detectors such as capacitance discharge or electromagnetic relays operative when proximate to a surface; photoelectric or other radiationsensitive means, etc. Similar surface detection means may be utilized in the apparatus hereinafter described to indicate the proximity of one or more surfaces for effecting automatic measurement functions.

Rotation of the assembly 30 relative to arm Ax may be effected by gear means as illustrated in my application Ser. No. 477,467. As shown in FIG. 1, reversible gear motor MA2, mounted within arm Ax, has a small bevel gear 30 secured to its output shaft which gear engages teeth of a larger gear 30 which is fixedly assembled with assembly 31 and is supported in bearing between portions of a yoke formation 30 projecting from the end of arm Ax. Thus, as motor MA2 operates, assembly 31 will pivot about the axis of joint 30, the direction and degree of which movement will depend on the rotation and degree of operation of MA2.

FIG. 2 illustrates a portion of an automatic measuring apparatus which may also have components provided in the apparatus of FIG. 1 or may be otherwise modified as hereinafter described. The assembly 10 includes in addition to a vertical column 23' which, like the column 13 of FIG. 1, may be stationary, longitudinally movable along a track, rotatable and/or pivotable and serves as means for supporting and guiding a plurality of measuring probe assemblies referred to by the notations 24a and 24b. The measuring probe assembly 24a is movable vertically up and down column 23' of a carriage or base 35a which also supports a motor MZl which is operative for vertically driving 350 up and down 23. Similarly the assembly 24b is supported on a base 35b adapted for up-anddown movement along column 23' and drivable by a motor MZ2 mounted thereon. The assembly 24a will be described and, for the purpose of simplifying the description, assembly 24b is shown as having similar components to those of 24a but referred to by similar numerical notations having subscripts b rather than a. Mounted on the lateral cylindrical column 36a is shown a gear motor MR0] having a small gear 27a pinned to the end of its shaft which engages a larger bevel gear 37a secured to a second arm Axa which is rotationally supported relative to 36a and rotatable with the operation of motor MRal. The other end of Ara is provided with a joint Jxa which pivotally supports a further arm A2xa for rotation about the axis of the joint. Secured to the end of arm A210 is a measuring probe Mla the end of which mounts a proximity sensing element Pa which is adapted to sense the presence of a surface of the workpiece when immediately adjacent thereto or in contact therewith. The sensing element Pa may comprise any known proximity-sensing transducer such as an electromagnetic proximity switch, the capacitance sensitive relay, photoelectric or other detector. In its simplest form, the sensing means Pa may comprise the actuating arm of a pivoting switch or limit switch.

As hereinabove described, a single programming controller such as CO mounted conveniently on or adjacent the column 23' and having control circuits extending therefrom and operatively connected to the various described drive servos of both assembles 24a and 24b may be utilized for precisely prepositioning the sensing means P of the probes relative to various surfaces of the workpiece W which may be prepositioned relative to assembly 10 on a movable conveying means which may be also controlled by CO or on a stationery prepositioning fixture.

Components of the assembly 24b which are the same as corresponding components of the assembly 240 have similar numeral notations with superscripts changed from a" to b."

While the two probe tips Pa and Pb of FIG. 2 are shown positioned for measuring the thickness of a shelf or horizontal projection Ws of the workpiece W, it is readily seen that by moving assemblies 240 and 24b along column 23, positioning by rotating, pivoting or otherwise moving 23', controlling motors MR4 and the motors pivotally positioning arms Ax2, the probes Mla and Mlb may be brought into contact with or adjacent many surfaces of a workpiece or assembly to effect measurement or locate said surfaces.

FIG. 3 shows details of a measuring head assembly 31 of the type illustrated in FIG. 1 which may be mounted at the end of the arm assemblies illustrated either in FIG. 1 or FIG. 2 or any suitable arrangement of movable components for prepositioning the assembly relative to a workpiece. In its simplest form, the assembly 31 of FIGS. 3 may be mounted stationary above a conveyor or other type of prepositioning means for the work W which is adapted to preposition the work relative to the illustrated separated jaws after which at least one of said jaws is automatically movable to engage a surface of the workpiece.

The assembly 31 comprises a first housing 34 illustrated as a cylindrical member which is removably secured to the end limb Ax which extends from a further stationary or movable base as illustrated in FIG. 1. The measuring probes comprise a first jaw member 33 which is movable towards and away from a second jaw member 32 which is shown secured by means of a block 32 to the end of 34. Movement of 33 is effected by means of a long, precision-cut lead screw 36' extending from an integral part of a shaft 36 which is supported in bearing by the end wall of 34 and bearing member 37 shown mounted within 34. A large spur gear 40 is secured to the end of 36 and is rotated to rotate 36 and the screw portion thereof by means of a smaller gear 39 secured on a shaft extending from a gear train assembly 38 which is driven by servomotor 37 secured within 34. A threaded bushing 35 is secured to 33 and is operative to cause 33 to move relative to 32 as 36 is rotated and along the polished surface of a rod 42 which extends through a bushing 33" extending through the upper portion 33' which bushing is slidably engaged against the surface of 42. Shown mounted within the hollow end of 33 and having an actuator arm projecting therefrom is a limit switch which is operatively connected to a control for stopping the operation of motor 37 through a plurality of wires, sliding contactors and the like including a first pair of wires 43 extending through 33 to a brush contactor 44 which rides on a strip conductor 45 inlaid in a channel in the upper surface of 42 and is insulated therefrom which is connected to a further wire pair 41 which extends along the inside of 34 and along the arm assembly and is operatively connected to the means for controlling the operation of the drive motor 37. A second limit switch 48 is mounted within arm 32 and has an actuator arm projecting outward therefrom in the direction of the arm 33. The switch 48 is operative to close upon movement of 32 against or in close proximity to a predetermined surface of the workpiece W and is utilized to energize the control for the motor or servo driving the assembly including 34 in the direction which urges 32 into close proximity or abutment with 31. The switch 48 is connected to said control through the wires included within the bundle 41 which extend directly to 48 through the center of member 32. A movable arm 50 is shown pivotally mounted at the end of 32 and normally projects beyond the plane in which the end of the actuator of switch 48 normally projects. The member 50 may be optionally applied to effect control of the motor moving the assembly including 34 so that it slows down when closely proximate to the surface of the work in the manner hereinafter described.

Notation MWB refers to a servo-operated means operatively connected to the conveyor or prepositioning table which is preferably controlled by the same programming control means controlling the position of the sensing assemblies described to project WB upward and the work thereon into a position between the jaws 33 and 32. The servo arrangement may be utilized with the apparatus illustrated in FIG. 1 or a modification thereof in which the jaws 32 and 33 are secured to a base such as 34 which is immovable.

Also illustrated in FIG. 3 are limit switches 48' and 49' having actuator arms protruding outward therefrom in opposite directions and are utilizable for measuring dimensions between surfaces which face each other such as inside diameters and the like.

FIGS. 4 and 5 illustrate a modified dimensional inspection head 50 having a plurality of probes, both of which are movable relative to each other and are utilized to sense the positions of opposite or aligned surfaces of a workpiece without resorting to the operation of limit switches, as taught in FIG. 3 to sense or indicate the position of said surfaces for measuring the distance therebetween. The probes 52 and 52 are movable in two directions relative to each other and may be program controlled to coact with each other in measuring distances relative to the sensing means of each or, to operate separately to measure spacial positions of various surfaces of a workpiece or assembly relative to a base or bench mark established by the mount or base supporting the head assembly 50. v

The assembly illustrated in FIGS. 4 and 5 comprises a base Ax which may be rigidly affixed on a support which is immovable or adjustably positionable relative to work to be measured or may be movable on the end of a fixture such as provided in FIGS. 1 or 2 or elsewhere in this application. Movement of base or arm Ax may be effected by automatic control and/or by means of a relay sensing the presence of the work or assembly to be measured which may be automatically conveyed into position as illustrated in FIG. 3.

Sensing head 52 is longitudinally movable outward from the end of base Ax by means of a motor 52M shown mounted within Ax and coupled by means of gears 51 to a geared bushing 51' which is internally threaded and adapted to engage and urge longitudinal movement of a threaded rod 53 which is connected at its outer end to sensing head 52. Notation 53 refers to a shafi secured at one end to 52 and slidably supported by bushings (not shown) with housing A.x to serve as a longitudinal guide for the head 52. Thus operation of reversible motor 52M will effect the movement of head 52 towards and away from the end of base Ax and if the gear ratio is sufficiently high, a complete rotation of said motor may result in a movement of the head 52 in the order of thousandths of an inch or less for precise positioning control.

A support 55 for head 52 is illustrated as being movable vertically relative to Ax and supporting 52' by means of a drivescrew 54 and shaft 54' operable to move 52 longitudinally relative to 55 by means of a motor mounted within 55 and gear train (not shown.) similar to the described drive means for 52. Base 55 is movable vertically relative to Ax by means of a drive similar to that provided within Ax and including a threaded shaft 56, equivalent to 53 in operation, along which the housing or support 55 is longitudinally driven by means of a threaded bushing similar to 51 which is rotationally supported within 55 and rotated through gears driven by motor 58. Notations 57 and 57' refer to shafts secured to Ax" which slidably support 55 to guide same in longitudinal travel thereon. The motor, gear train and threaded bushing operatively connected to threaded shaft 54 are assumed to be mounted within 55 though not shown.

lnsulatedly supported on each of the heads 52 and 52 are respective sensors 58 and 59 which may comprise pieces of metal of any suitable shape although illustrated as conforming to the shape of the portion of the heads to which they are secured. The probe ends 58 and 59 are adapted to be driven into contact with the work and to complete an electrical circuit therewith or to sense the presence of the surface of the work by electromagnetic or capacitance means. In other words, though not shown, members 58 and 59 are assumed to be in respective sensing circuits including relay means energizable upon positioning each probe end against or immediately adjacent a surface to be measured to generate a signal for affecting such measurement.

Notations 58 and 59 refer to strips of insulation material disposed between head sensing elements 58 and 59 and their respective bases 52 and 52.

The heads 58 and 59 may be removable for replacement to provide difl'erently shaped surface-sensing devices to conform to different workpieces. Said heads 58 and 59 may also be adjustably positionable relative to their respective mounts if movably mounted thereon and provided with locking screw adjustment means of conventional design to conform to different measurement functions.

FIG. 6 illustrates components of a measurement assembly which is a modification of that illustrated in FIG. 2. Two surface-sensing probes MI and MI are shown respectively mounted on heads A4 and A4 each of which is provided with a respective joint J3 and J3 for pivotal movement relative to second arm members A3 and A3. The arm members A3 and A3 are further pivotally supported and rotated on joint as semblies and J2 and J2 about further arm members A"and a which are similarly pivotally supported on arm member A1 and Al, the latter being fixedly mounted on a common base. Each of the arm members A2 to A4 is power rotated relative to the member on which it is mounted by means of a respective motor provided within the arm member and the motors are all numerically controlled by signals generated, for example, by a programming means such as a computer operated by means of a magnetic tape. Ifthe base on which Al and A1 are mounted is rotatable on a further base by means of a servomotor also controlled by signals generated as reproduced from the same tape controlling the other servos, then it is easily seen that the sensing heads MI and MI may be positioned at substantially any two points or positions in the spacial volume attainable thereby and the positions of said heads will be a function of the number of rotations of each of the motors driving the arms A and the length of each arm.

In FIG. 7 is illustrated a block diagram showing means for effecting positioning control of the probe arms 32 and 33 of measurement head 31 illustrated in FIGS. 1 and 3 and it is noted that the control system and components illustrated may also be applicable to the other apparatus such as illustrated in FIGS. 2, 4, 5 and 6 by appropriate modifications thereto. Motor Mx is operative for driving the base on which housing 34 is supported in a longitudinal direction for positioning the probe head 32 relative to a surface to be sensed thereby. Motor My is operative for positioning the entire assembly 31 along a track such as illustrated in FIG. 1 although the use of My may be optional, particularly if a conveyor such as W8 is utilized for positioning the work W relative to the fixture. The motor Mz is operative for moving assembly 31 in the vertical direction and again may or may not be utilized depending on the characteristics of the work being measured and how it is prepositioned relative to the measurement head. If the apparatus of FIGS. 4 and 5 is employed, motor Mz may be equivalent to servo 58 and a plurality of servos each operative to move a respective head relative to the work may replace Mx.

A positional computer CO is employed which includes a programming means 66 which may comprise a tape or card reading device having conventional means for generating a programmed sequence of signals such as digital signals which are fed to preset predeterrnining controllers 67 and 69. The circuitry in controller 67 is operative after being preset by command signals transmitted thereto from programming input device 66, and upon energization of a start-cycle input 68 to generate a plurality of control signals on plural outputs thereof which are operative to sequentially control each of the illustrated drive motors by energizing the controls of said motors either for predetermined periods of time or to effect respective predetermined degrees of rotation of each motor by feedback signals generated in response to means for counting said rotations. The start-input 68 for the controller 67 is energized when a sensing device such as a photoelectric cell and relay 60 mounted on the housing 34 on which probe 32 is secured, scans and becomes activated when light from a source 61 secured on the other side of the work W is interrupted by said work. The output of 60 is passed as a signal to start control 68 whereafter signals are generated thereby for controlling the various servos including the operation of probe motor 37 to preposition probe head 33 adjacent the surface W2 of work W. Thereafter 67 controls the operation of motor Mx whereby probe head 32 is driven towards the other face W1 of the work W until switch 48 becomes activated upon contacting said surface. Upon the actuation of the switch 48, a signal is generated on the output 48a thereof which is transmitted to the stop-control S of motor Mx positioning head 32 against face W1 of the work. The signal generated upon closure or activation of switch 48 is also passed to the reverse drive input R of motor 37 whereafter the arm 33 is driven towards face W2 of W until switch 49 closes upon contact therewith and generates a signal on its output 491: which is passed to the stop control S of motor 37 and also to an energizing input 70 of controller 69 which is thereafter operative to control the various servomotors to effect opening of the probes 32 and 33 and the withdrawal of the fixture 31 from the work, if necessary, to permit removal of the work and the advancement of a new work member to the vicinity of the measuring apparatus.

An indication of the degree the probe members 32 and 33 are separated upon predetermined positioning or contact with respective surfaces W1 and W2 of the work, is attained by means of a counter 62 counting rotations or fractions or rotations of the lead screw shaft 36 whenever a cam 36c which is secured to said shaft, actuates the actuator arm of the counter. Counter 62 is provided with a trigger input 63 which is connected for receiving the signal generated by switch 49 when actuated upon movement of 33 against or adjacent surface W2. Upon receiving such energizing signal, the counter 62 is operative for generating a code signal on an output 63' thereof which is transmitted to a device 64 for recording said code and/or performing computing functions utilizing said code. The device 64, for example, may include a servo and computing circuitry for operating said servo when the separation of the probes 32 and 33 exceeds or falls within a predetermined distance or range of distances for effecting the further handling of the workpiece in a predetermined manner. Notation 71 refers to the motor driving conveyor WB which receives a signal from a delay relay 70 which is energized when switch 49 becomes activated. The operation of 71 to move W away from the probe head 31 is delayed a sufficient period of time to permit the withdrawal controller 59 to command operation of motors Mx and 37 to open the probe anns 32 and 33 a sufficient degree so that the work is not engaged thereby and will clear the fixture upon operation of 71. Prepositioning of the work W relative to 31 is affected when the output of photoelectric relay controller 60 is passed to the stop control S of motor 71.

Also illustrated in FIG. 7 are slowdown controls 50 and 50 for motors Mx and 37 which controllers are illustrated in greater detail in FIG. 8. The controller 50' is shown in FIG. 8 and controller 50' is similar in function thereto. Said controller includes a pivotally mounted actuator arm 72 having an end portion 72 projecting substantially beyond the end of the actuator of the limit switch 49 and adapted to first engage the surface of the work immediately adjacent said limit switch. The arm 72 pivots and in doing so causes an electrical wiper section 73 thereof to sweep across a surface resistance element 74 and increase the resistance of a circuit including a controller 76 for the motor 37. The controller 50' may be a speed control such as a rheostat supplying current to the armature of a direct current motor such as 37, the speed of which varies proportionally to said current. Hence, the closer probe head 33 gets to the surface W2, the slower motor 37 will operate so that said probe head will slow down substantially prior to being stopped and gently contact or be prepositioned relative to said surface W2. Notation 75 refers to the pivot which arm 72 maintains contact with to complete the circuit through said arm and including resistance element 74, power supply PS and control P for motor 37.

Notation 50h refers to the wall of the housing or am 50 and 50h to the opening therein through which arm 72 projects.

FIGS. 9', 9 and 9a shown details of a system for effecting dimensional measurement of an article or assembly by controlled movement of a scanning head relative to a predetermined surface of said article and the automatic detection of predetermined variations or changes in the optical characteristics of said surface for electrically indicating either distances across predetermined portions of the article such as aligned or opposite surfaces or predetermined variations in dimensions of an article from a standard or known value. A workpiece WK is shown as a sheet or stablike structure having a plurality of stepped indentations in one edge thereof across which it may be desired to measure distances such as D1, D2, D3, etc. The measuring head assembly 80, in this instance, comprises a U-shaped mount 81 for a light source 83 and the photoelectric detector or cell 84 which are mounted on opposite legs 81a and 81b of the frame 81 and positioned such that a light beam generated by the light source 83, will ordinarily pass to the photoelectric cell in housing 84 and will effect the energization of said cell so as to produce a signal on its output. If the light source is interrupted by, for example, positioning a portion of the work WK between said light source and the photoelectric cell in 84, the signal output of 84 will cease. Variations in this arrangement may also include the generation of an electrical signal on the output of scanner 84 when no light appears from light source 83 which operation will depend on the phenomenon or articlebeing measured. This may be effected by providing the proper control or switching means within the photoelectric relay housing 85 the output of which is shown connected to a computing device 86 including means for generating a signal or signals on an output 87 thereof which signals may be recorded orrotherwise utilized as hereinafter described.

The control computer CO includes means in the form of recordings on a magnetic tape, for generating a plurality of command signals which are operative to preposition the scanning assembly 80 relative to the workpiece WK and/or the workpiece relative to said scanning assembly. The scanning head 80 may comprise any suitable surface detection and transducing means including, in addition to the arrangement provided in FIG. 9, surface-contacting means such as illustrated in FIGS. 3 to 6 and means of the type illustrated in FIG. 1 and 2 for prepositioning and conveying said head assembly relative to a workpiece or assembly to be measured thereby. The U-shaped frame or mount for 81 is shown secured to an arm Ax which may comprise the terminal limb or arm of a plurality of such arms such as illustrated in FIGS. 1, 2 or 6 and including adjustably movable components for moving said scanning or surface-detection means mounted thereon by the controlled operation of a plurality of servomotors referred to by the notations Mx, My, Mz, MR, MAx', etc. These motors are shown having their control inputs operatively connected to a positional control computing device 89 which is operatively connected to a plurality of reproduction heads 90 positioned for reproducing command recordings on respective channels C of a magnetic recording tape 91 for predetermining the path of movement of the measurement head assembly 80 and/or the work WK.

Signals recorded on one of the channels of a first bandlike command recording area CA1 of the recording member 91, are reproduced therefrom in synchronization with the reproduction of the command recordings which position the measurement head 80 and are passed to a circuit 92 connected for conditioning the counting device in the distancecomputing device 86 to become active for receiving a signal generated by the photoelectric relay 85, so that, during prepositioning said relay before the photoelectric cell in 85 is aligned with a portion of the work WK and receiving light from light source 83, the counter in 86.will not become activated. In other words, signals recorded on the commandrecording portion CA1 of 91 are utilized not only to preposition the measuring assembly 80 and the work but also to activate and deactivate the counting or measuring circuits in 86 so as to be active only during that portion of the measurement cycle during which scanning is effective to perform dimensional measurement. In measuring the dimension D1, for example, a signal reproduced from the tape and generated on control input 92 to 86 is generated to activate the measuring circuit or counter therein only during the interval the photoelectric relay is aligned with and scanning a path defined by limiting points illustrated at D1 and D1. The photoelectric relay in housing 84 becomes active to gate or energize the counter in 86 only after its scanning axis has passed the edge of the work WK inward of point D1 and generates a signal for gating said counter until said scanner is conveyed past the edge inward of D1. The resulting numerical value of the counter in 86 is automatically converted to a proportional binary or code signal generated on an output 37 connected to a recording head or bank of heads 88 which are operatively coupled to the recording member 91 for recording on a channel or channels defined by bank-recording area CA of the same tape from which the positional command recordings were reproduced. The energization or readout of the counter in computing device 86 may also be effected by reproduction of a signal from the command-recording area 91 which is generated on the control line 92 and passed to 86.

By utilizing the recording and command control arrangement of FIG. 9, signals are automatically provided on the signal-recording member 91 which are indicative of the dimensions measured and are recorded in predetermined positions relative to the positional command recordings. In other words, the positions of the newly recorded dimensional signal on the recording member are indications of which dimensions were so measured. Since the apparatus provides means for predetermining the location of dimensional indicating signals, other signals may be prerecorded on other channels or bank recording areas of the recording member 91 such as CA3 and CA4 which will be indicative of standard or predetermined dimensions such as required of the measured dimension for it to conform to a predetermined value or to fall within a predetermined tolerance range. Before describing the function and operation of comparator means illustrated in FIG. 9 for comparing actual measurements with predetermined standards, reference is made to FIG. 9' which shows further details of the computing device 86. Said device may comprise a pulse counter 86c having an input 860' which is the output of a pulse generator 86b, which is activated to generate a train of pulses of the same time duration and repetition frequency whenever an input 86b thereof is energized by a signal from the photoelectric relay provided that a nonnally open switch 86a in the output of 85 is closed by a signal generated on line 92 and reproduced from a channel of recording member 91 in predetermined time relation to the other positional command signals such as during the interval the scanning axis of the photoelectric cell PH in housing 84 passes between points D1 and D1 along the surface of the work which includes the dimension to be measured. In other words, pulse generator 86b is activated to generate a train of pulses on its output 86c only during that interval the actual dimension to be measured is being scanned and the number of pulses gated to the input of counter 860 is proportional to the actual dimension so measured.

After receipt of the chain of pulses generated in scanning the dimension in question, the counting device 860 may be provided with automatic means for generating a code on its output 87 which may be passed directly to the recording heads 88 and recorded on the recording area CA5. Illustrated in FIG. 9' is a control 86d which is energized by a signal on the input 92 generated in predetermined time relation to the movement of the inspection head conveying apparatus as reproduced from a channel of the command signal recording area CA2. When control input 86d is so energized, it is operative to effect the generation of said dimension-indicating pulse train or binary code on the output 87 of 860 which may be directly recorded on a single channel or, as illustrated in FIG. 9', may be passed to a shift register 862 where it is converted to parallel code generated on a plurality of outputs 88 which extend to a bank 88 of recording heads for recording on respective channels of the area CA5 of the recording member 91.

It is noted that other forms of command signal recording may also be employed to effect the program control hereinabove described and to generate said signals which are indicative of standard or desired dimensions. Reading arrangements employing recordings on punched cards, punched tape or other forms of recording may replace or supplement the described magnetic recording arrangements.

Although control of the position and path of travel of the measuring head or probe assembly '80 relative to the work WK may be effected by the continuous movement of the recording member 91 past reproduction heads for reproduction of the positional command recordings, in certain modes of automatic measurement it may be advantageous to stop the travel of the tape during periods when automatic computations, recordings, or the like are being made. Accordingly, signals may be recorded on bank recording area CA1 which are reproduced by a pickup head 93 and passed to a controller 93 controlling operation of the motor MT driving the tape, to stop movement of said tape and later resume its movement past said reproduction heads. Motor MT may be automatically restarted by a time-delay relay control or by a signal generated on an output such as 87 of code generator counter 86.

It is briefly noted that the counter in computing mechanism in 86 may also include means for visually indicating the value of the dimension being automatically measured for local immediate monitoring.

Referring now to recording areas defined by notations CA3, CA4 and CA5, it is noted that the reproduction heads or bank of heads referred to by the notations P3, P2 and P1 are respectively positioned for reproducing from said respective reproduction areas of said recording tape. As stated, recording area CA contains signals indicative of the actual dimensions measured as recorded through recording head bank 88. Prerecorded or predetermined lengths of the recording area CA4 are a plurality of signals or groups of signals which are indicative of standard or desired measurements with each group being provided in such a position that it may be reproduced simultaneously or in predetermined time relation to the reproduction of a signal or group of signals recorded on channel CA5 relating to the dimension measured by the scanning apparatus to be compared with a predetermined value. In other words, since the recordings on channel CA4 are prepositioned relative to the positional command recordings on channel or area CA1 and furthermore, since the recordings of actual scanning on CA5 are prepositioned relative to said same positional command recordings, then the standard recordings will be prepositioned relative to the actual recordings on CA5. Each associated group of recordings is reproduced and amplified in respective amplifiers 94 and 95 and passed on respective output circuits 94 and 95' to a comparator device 96 where the signals are compared and the difference or variations therein are computed. A visual or signal indication of the difference of the measured dimension from the standard dimension is provided by a second comparator 98 which is shown as having a further input 97' from a further reproduction-transducing means P1 which is operatively coupled to channel CA3 on which may be recorded nominal or standard groups of signals each of which is equivalent in numerical value to an acceptable range of variations of the measured dimension from the standard dimension and is operative, upon being reproduced and transmitted on the output 97' to the comparator device 98 to determine if the measured dimension falls outside of or within the predetermined tolerance range. Accordingly, a second comparator 98 is provided to accept both the difference signal generated by comparator 96 and that reproduced from channel CA3 and is adapted to generate a signal or signals on its output 99 which are indicative as to whether or not the image measured falls within or beyond the predetermined tolerance range which signals may be recorded in a further recording device 100, which may be used merely for record-keeping purposes, as a means for providing dimensional codes or code indications or variations of dimensions from tolerance for immediate or later computer analysis. The device 100 may also contain an alarm means for indicating by visual means or sound to an operator when a dimension so measured falls outside of the tolerance range as determined by recordings on channels C3 and/or C4.

A complete description of the control apparatus for conmined degrees and paths to cause the measuring probe or head to be prepositioned relative to a workpiece and to thereafter move in a predetermined path in scanning or sensing various portions or surfaces of the workpiece is brief since it is not claimed specifically herein. Various automatic control systems for predetermining the path of movement of machine tools are known in the art and reference is made to -U.S. Pat. Nos. 2,475,245 and 2,7l0,934.

tinuous shaft rotation by reproducing impulses from a respec-- tive channel or channels of the recording member 91 which are converted to a binary code by a diode converter 106 which code is used to set up a relay storage bank 107 containing precision resistors. The contacts of the storage unit relays set up the resistance bank in 107 so that the value set up is protrolling the various conveyor components to travel predeterportional to the digital information recorded on the tape 91. The relay storage introduces a resistance proportion to the numerical value of the signals reproduced from the tape into a self-balancing bridge which forms part of a comparator device 108. A feedback signal generated during the operation of the servomotor being controlled, such as by means of a response potentiometer 109 which is coupled to the shaft of the control motor, provides an error signal at the output of the comparator 108 which is used to control the operation of said motor until the bridge is balanced or a null condition exists whereupon the motor will stop with the component or assembly driven thereby being at a predetermined spacial position as commanded by the code on the tape. Other signals reproduced from the magnetic tape 91 are positionally provided to operate others of the motors positioning the fixture or measuring head in a predetermined sequence with each servo controlled also thereby so that said measuring head or probe will travel a predetermined path or contour relative to the workpiece.

Of course, other path-determining means such as contour following means may also be utilized to effect such bathpredeterrnining controls.

While a photoelectric cell and light source 83 are provided in FIG. 9 for scanning and indicating the position of various edges of the workpiece to effect automatic measurement thereof, it is noted that the control apparatus as well as the recording, reproduction and comparator means of FIG. 9, 9' and 9a may be applied for controlling and effecting automatic measurement with the probe-contact or surface-sensing apparatus provided elsewhere herein such as illustrated inFIGS. 1 to 8.

It is further noted that the train of pulses utilized for measuring the degree of movement of the probe or measurement head between or across predetermined surfaces may be effected by actuation of a limit switch by means of the rotation of the particular motor utilized in moving said probe or head between said surfaces.

Other forms of radiation such as an X-ray generator, source of nuclearenergy, infrared generating means and selective detection means may also be utilized and may replace or supplement the photoelectric detection means and light source provided in FIG. 9. g

It is also noted that the limit switch surface-sensing means provided herein may also comprise a fluidically operated sensor such as a fluid amplifier operative to detect a surface when air ejected thereby or from a nearby nozzle is interrupted by the work or is varied sufliciently in its flow to permit the detector to generate a fluidic detection pulse which may be utilized to effect measurement and control functions as described by activating suitable fluidic control devices which are the fluid equivalents of these herein described.

In another form of the invention, the image area, workpiece or component being measured may be supported on a mount or conveyor therefore and predeterminately positioned and moved past scanning means such as the type described to effect such automatic measurement or indication that the dimension being measured is within or out of a predetermined tolerance range. Any suitable conveyor or manipulator for the work which will predeterrninately position and move the work past the optical gauging light source and photosensor while said devices are held stationary may be employed and, like the movable mount for the light source and scanner heretofore "described, may be numerically or otherwise automatically controlled to move the workpiece or image being scanned through a predetermined path or paths.

The described scanning system employing an aligned and spaced-apart light source and photoelectric cell may be replaced by any suitable photosensing system including one containing an electron gun with a deflection-controlled electron beam, an X-ray generating gun for measuring internal dimensions, or a light source mounted at the side of or in direct alignment with a photosensor adapted to receive light from the source reflected from the surface being scanned and to indicate variations in said surface or when the scanner has scanned beyond an edge thereof by failure to receive reflected light therefrom.

In still other forms of the invention, the apparatus of FIGS. 9, 9' and 9a or modifications thereof may be utilized for scanning and measuring or digitizing photographed or optical images of various objects or other physical phenomena. The workpiece WK may be replaced by photographic film or an imaging screen on which the image or a shadow of the object to be scanned has been projected or otherwise provided. The photosensor 84 may comprise a flying spot scanner or conventional television scanning camera operative to generate an output signal which may be digitized as described. Or, said output signal may be analyzed and digitized by a computing device as provided in my copending patent application Ser. No. 267,377 and US. Pat. No. 3,081,379. If a filmstrip is utilized containing a tandem array of frames to be individually beamscanned, the beam-generating apparatus and filmstrip may be controlled in operation as provided in my copending applications, Ser. Nos. 219,609 and 123,327.

In FIG. 13 is shown a modified form the instant invention in which a code indication is provided of the position of the probe at'the instant it senses the surface being measured or mapped and said code is in such a form as to be utilizable by a computer or comparator for performing one or more functions such as dimensional measurement, variation from tolerance, visual indication or printout of the position of the surface or other indication defined by the degree of movement of the probe. The apparatus 110 includes an automatic manipulator including a probe manipulation arm 111 movable per se or terminating one or more other manipulation arms as described herein, the arm 111 being connected by a suitable coupling means 112 to the output of a motor 113 which is automatically controlled by a master controller 116 such as a computer or tape reader as described. A plurality of command control outputs 116 from the master controller 116 control not only the probe motor 113 by pulsing or otherwise operating the forward, stop and reverse controls 114 therefore but also the other arms or components of the manipulation apparatus 1 10 such as those hereinbefore described.

Secured to the probe manipulator arm 111 and preferably projecting from a wall thereof so that it may be photooptically scanned is a thin strip or bar 120 of optical glass containing a binary digital code scale 121 or other suitable form of parallel code which is printed, etched or photographically formed in the bar 120 and extends parallel to the longitudinal axis thereof or the direction of movement of the arm 11] with respect to a mount 122 for a plurality of photooptical scanning transducers 123 and a light source 119. The light source 119 generates a sheet of light denoted 119B which is passed through the code scale 121 of the bar 120 which scale operated to block light to certain of the transducers 123 which are formed in a bank, while permitting light to pass to others of the transducers. The transducers 123 are thus energized and deenergized in accordance with those opaque and transparent areas of the parallel code 121 of the bar 120 and operate to provide signals on certain of the outputs 124 of said transducers while the other outputs are deenergized in a coded array such as a binary code. A plurality of normally open monostable switches 125 are provided in the outputs 124 which switches extend from a pulse transformer 128. When the input to the pulse transformer 128 in energized by a pulse, simultaneous pulses are generated on the outputs 127 of the pulse transformer 128 and operate to momentarily close the switches 125 thereby gating the outputs 124 of the scalescanning transducers 123 to respective parallel output circuits 126 which may extend to a comparator device operative for comparing the code with a recorded or predetermined code to determine if the location of the surface measured or sensed is a predetermined value. The outputs 126 may also be connected to a visual presentation means such as a digital character display, a printer and/or a summing circuit operative to provide a code or numerical indication of the location of the surface sensed by the probe or the location of the probe from a base location at the instant the transformer 128 is pulsed.

The pulse transformer 128 thus has an input 118 extending from the surface-sensing sensor or transducer 117 which, as described, may comprise a limit switch or other means for sensing a surface against which or near which it is driven. The sensor 117 is shown mounted at the end portion 111' of the arm 111. A second input 118 to the pulse transformer 128 is illustrated which second input may be derived from a controller or computer operative to generate a pulse signal at intervals when it is desired to determine the location of the probe arm in space such as the distance travelled by said probe from a known location or base. Notation 116' refers to feedback inputs to the master controller for transmitting feedback signals, as described, to effect or control probe manipulator movement.

The automatic measurement system of FIG. 13 employing a bank of transducers such as photomultiplier tubes forming a stack 123' to scan a code scale which is fixed with respect to the probe arm, has an additional advantage in that automatic control and measurement may be effected without the necessity of completely retracting the probe arm to a home location prior to the next measurement function or operation as is required of an apparatus using pulse-counting means to effect measurement. If the signals generated by master controller or computer 116 are such as to cause the sensor 117 to be conveyed across a surface and against or close to the surface at predetermined intervals, signals may be generated on the outputs 126 which may indicate, in parallel code form, the general contour or mapping of the surface so scanned. The probe arm 111 may also be controlled to cause the probe sensor or an extension thereof to engage and conform to a surface as it is conveyed in a predetermined path across the surface with a pulse-generating means or the master controller or computer 116 operative to pulse the transformer 128 at fixed intervals for generating codes which are indicative of the contour of said surface.

I claim:

1. A automatic inspection apparatus comprising:

a. a transducer;

b. a support for said transducer;

c. a base for moveably supporting said transducer support;

d. means for prepositioning a work piece with respect to said base;

e. means for guiding said transducer support in a path to bring said transducer into sensing relationship with respect to a surface of said work piece to be measured;

f. means for energizing said transducer to generate a control signal upon sensing said surface;

g. means operative when said transducer is moved for generating information signals indicative of the degree of movement of said transducer with respect to said base;

h. digital indicating means operative to receive said information signals generated as said transducer moves with respect to said base for visually presenting said information; and

i. means responsive to said control signal for controlling the operation of said digital indicating means to visually present information indicative of the degree of movement of said transducer and the location of the surface sensed by said transducer.

2. An automatic inspection apparatus in accordance with claim 1, said visual presentation including a digital indication means which is readable to indicate the degree of movement of said transducer from a predetermined location.

3. An automatic inspection apparatus in accordance with claim 1, said visual presentation means including a printer operative for printing said infonnation in readable form.

4. An automatic inspection apparatus in accordance with claim 1, including an indicating alarm means for visually indicating when the dimension defined by said digital-indicating means is out of tolerance.

5. An automatic inspection apparatus in accordance with claim 1, said means generating information signals comprising a readable code scale connected to said transducer support and scanning means for scanning said scale as the support moves.

6. An automatic inspection apparatus in accordance with claim 5, said scale having a binary digital code disposed in parallel array along its length, and means operative when the transducer support moves for reading said digital code and generating said information signal.

7. An automatic inspection apparatus in accordance with claim 1, further including control means for each of said motors and master control means operatively connected to each motor control means for predeterminately activating same to cause each motor to predeterminately drive said transducer support in respective directions relative to said means for prepositioning said work whereby the transducer is controlled to travel a predetermined path with respect to the work.

8. An automatic inspection apparatus in accordance wi h claim 1, including power-operated means for driving said transducer support in a plurality of directions.

9. An automatic inspection apparatus in accordance with claim 8, said power means including at least two motors, one of which is operative to drive said transducer in a first direction and the other being operative to drive said transducer in a second direction.

10. In an apparatus for automatically measuring dimensions:

a base;

a probe movably supported on said base;

work-holding means for prepositioning a unit of work with respect to said base;

motor means for driving said probe towards and away from said base;

feedback signal generating means operative with the movement of said probe for generating signals which vary in number as the probe moves, said signals being indicative of said probe movement;

first means for initiating operation of said motor means to effect movement of said probe from a first location away from the surface of said work to be measured towards said surface;

means operative to receive said feedback signals and to convert said signals to digital information;

sensing means supported by said probe for locating and sensing a surface;

said sensing means being operative to generate a control signal upon sensing a surface;

summing means operative to receive and sum said digital information;

means connected to said summing means for indicating the degree of movement of said probe;

control means for said summing means and said indicating means;

said control means being operatively connected to said sensing means and being responsive to said control signal for causing said summing means to activate said indicating means upon the sensing of a surface by said sensing means whereby an indication is had of the location of said surface.

11. An automatic inspection apparatus in accordance with claim 10, whereby said indicating means is operative to present visual digital information indicative of the location of said surface.

12. A method for automatically measuring dimensions comprising:

predeterminately locating a member containing dimensions to be measured and a surface-sensing probe;

relatively moving said probe and said surface;

generating pulse signals with said relative movement and feeding said pulsed signals to a summing means;

summing said pulse signals derived from said relative movement; indicating when said probe senses the the surface by generating a control signal; 7

applying said control signal to control the summing of said pulse signals whereby the pulse signals generated at the time said surface is sensed by said probe are presented in the form of digital infonnation on the output of said summing means; and

applying said digital information signals to activate a visual presentation means to visually indicate the distance travelled by said probe in intelligible form. 

1. A automatic inspection apparatus comprising: a. a transducer; b. a support for said transducer; c. a base for moveably supporting said transducer support; d. means for prepositioning a work piece with respect to said base; e. means for guiding said transducer support in a path to bring said transducer into sensing relationship with respect to a surface of said work piece to be measured; f. means for energizing said transducer to generate a control signal upon sensing said surface; g. means operative when said transducer is moved for generating information signals indicative of the degree of movement of said transducer with respect to said base; h. digital indicating means operative to receive said information signals generated as said transducer moves with Respect to said base for visually presenting said information; and i. means responsive to said control signal for controlling the operation of said digital indicating means to visually present information indicative of the degree of movement of said transducer and the location of the surface sensed by said transducer.
 2. An automatic inspection apparatus in accordance with claim 1, said visual presentation means including a digital indication means which is readable to indicate the degree of movement of said transducer from a predetermined location.
 3. An automatic inspection apparatus in accordance with claim 1, said visual presentation means including a printer operative for printing said information in readable form.
 4. An automatic inspection apparatus in accordance with claim 1, including an indicating alarm means for visually indicating when the dimension defined by said digital-indicating means is out of tolerance.
 5. An automatic inspection apparatus in accordance with claim 1, said means generating information signals comprising a readable code scale connected to said transducer support and scanning means for scanning said scale as the support moves.
 6. An automatic inspection apparatus in accordance with claim 5, said scale having a binary digital code disposed in parallel array along its length, and means operative when the transducer support moves for reading said digital code and generating said information signal.
 7. An automatic inspection apparatus in accordance with claim 1, further including control means for each of said motors and master control means operatively connected to each motor control means for predeterminately activating same to cause each motor to predeterminately drive said transducer support in respective directions relative to said means for prepositioning said work whereby the transducer is controlled to travel a predetermined path with respect to the work.
 8. An automatic inspection apparatus in accordance with claim 1, including power-operated means for driving said transducer support in a plurality of directions.
 9. An automatic inspection apparatus in accordance with claim 8, said power means including at least two motors, one of which is operative to drive said transducer in a first direction and the other being operative to drive said transducer in a second direction.
 10. In an apparatus for automatically measuring dimensions: a base; a probe movably supported on said base; work-holding means for prepositioning a unit of work with respect to said base; motor means for driving said probe towards and away from said base; feedback signal generating means operative with the movement of said probe for generating signals which vary in number as the probe moves, said signals being indicative of said probe movement; first means for initiating operation of said motor means to effect movement of said probe from a first location away from the surface of said work to be measured towards said surface; means operative to receive said feedback signals and to convert said signals to digital information; sensing means supported by said probe for locating and sensing a surface; said sensing means being operative to generate a control signal upon sensing a surface; summing means operative to receive and sum said digital information; means connected to said summing means for indicating the degree of movement of said probe; control means for said summing means and said indicating means; said control means being operatively connected to said sensing means and being responsive to said control signal for causing said summing means to activate said indicating means upon the sensing of a surface by said sensing means whereby an indication is had of the location of said surface.
 11. An automatic inspection apparatus in accordance with claim 10, whereby said indicating means is operative to present visual digital information indicative of the location of said surFace.
 12. A method for automatically measuring dimensions comprising: predeterminately locating a member containing dimensions to be measured and a surface-sensing probe; relatively moving said probe and said surface; generating pulse signals with said relative movement and feeding said pulsed signals to a summing means; summing said pulse signals derived from said relative movement; indicating when said probe senses the the surface by generating a control signal; applying said control signal to control the summing of said pulse signals whereby the pulse signals generated at the time said surface is sensed by said probe are presented in the form of digital information on the output of said summing means; and applying said digital information signals to activate a visual presentation means to visually indicate the distance travelled by said probe in intelligible form. 